Photochemically promoted regiospecific P–C bond cleavage in the diruthenium compound Ru2(CO)2(bmf): X-ray diffraction structure of Ru2(CO)6[μ-C=C(PPh2)C(O)OCH(OMe)](μ-PPh2)

Abstract

The ruthenium cluster Ru3(CO)12 reacts with the diphosphine ligand 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf) in refluxing toluene to furnish the donor–acceptor compound Ru2(CO)2(bmf) as a 1 : 1 mixture of diastereomers. Photolysis of Ru2(CO)2(bmf) using 366 nm light leads to the oxidative cleavage of a P–C bond and formation of the phosphido-bridged complex Ru2(CO)6[μ-C=C(PPh2)C(O)OCH(OMe)](μ-PPh2). The regioselective Ph2P–C(furanone ring) bond activation attendant upon optical excitation is traced to the phosphine group that was β to the furanone carbonyl group, as established by X-ray analysis of one of the diastereomers of Ru2(CO)6[μ-C=C(PPh2)C(O)OCH(OMe)](μ-PPh2). Both diruthenium products have been fully characterized in solution by IR and NMR (1H and 31P) spectroscopies and elemental analyses. The observed regioselectivity associated with the P–C bond activation in Ru2(CO)2(bmf) is discussed with respect to the chemistry of other bmf-substituted compounds prepared by our groups.